A typical vane-type camshaft phaser generally comprises a plurality of outwardly-extending vanes on a rotor interspersed with a plurality of inwardly-extending lobes on a stator, forming alternating advance and retard chambers between the vanes and lobes. Oil is selectively supplied and vented to and from the advance and retard chambers in order to achieve a desired phase relationship between the rotor and the stator, and consequently, a desired phase relationship between a camshaft and a crankshaft of an internal combustion engine. The supply and venting of oil to and from the advance and retard chambers is typically controlled by a valve spool. For packaging benefits the valve spool may be positioned within a bore of a centrally located camshaft phaser attachment bolt which is used to attach the camshaft phaser to the camshaft. United States Patent Application Publication number 2012/0060787 A1 shows such a camshaft phaser with the valve spool located within the centrally located camshaft phaser attachment bolt. In order to filter oil being supplied to the valve spool and in order to prevent oil from flowing backward from the valve spool to the oil source, a combination filter and check valve is provided within the same bore as the valve spool. The filter includes two annular sections separated from each other and connected by four struts. A cylindrical filter fabric is arranged around the struts between the two annular sections. A check valve body in the form of a ball is positioned within the struts and the struts act to guide the ball axially. When pressure within the camshaft phaser is elevated to a pressure that is higher than the oil source, the ball is seated against a shoulder in the bore to prevent backflow of oil to the oil source. While this filter and check valve arrangement may be compact, the location of the filter within the camshaft phaser attachment bolt renders the filter unserviceable in the event the filter becomes plugged during operation. The location of the filter also renders the available filter area to be small which may make the filter susceptible to plugging.
What is needed is a camshaft phaser which minimizes or eliminates one or more of the shortcomings set forth above. What is also needed is a check valve and filter arrangement for a camshaft phaser which minimizes or eliminates or more of the shortcomings set forth above.